Maybe up to around 13MHz at the moment. Give it a few years and it will be above 20MHz. 21.885MHz used to be a 'Speedbird' (ah - BOAC!) calling frequency some 35 odd years ago when we higher up in the sunspot cycle, although that was mainly on North - South routes.
Funny to think that the job of Flight Radio Officer came and went in under 40 years, isn't it? Even Flight Engineers lasted longer...